Weed Management in Single- vs. Twin-Row Peanut (Arachis hypogaea)1

Experiments were conducted in Florida in 2000 through 2003 to evaluate weed management systems in single- and twin-row peanut utilizing either conventional or strip tillage. Diclosulam or flumioxazin preemergence (PRE) or 2,4-DB or imazapic mid-postemergence (MPOST) or late-postemergence (LPOST) was needed for greater than 95% common cocklebur control in conventional- and strip-tillage peanut. In both tillage systems, paraquat + bentazon early-postemergence (EPOST) followed by (fb) 2,4-DB or imazapic MPOST, 2,4-DB or chlorimuron LPOST, or both was required for more than 80% late-season control of Florida beggarweed and control in twin-row was 5 to 10 percentage points above that observed with single-row peanut. Paraquat + bentazon EPOST preceded by a diclosulam or flumioxazin PRE or fb MPOST or LPOST applications provided 80% or greater control of ivyleaf morningglory, and no differences were observed between peanut planting pattern. Paraquat + bentazon EPOST fb imazapic MPOST was the only treatment that provided 90% or greater late-season sicklepod control across all years and tillage methods, and, regardless of tillage, sicklepod control was 7 percentage points better in twin- than single-row peanut. Treatments that contained diclosulam or flumioxazin PRE and paraquat + bentazon EPOST fb a MPOST or LPOST herbicide application increased peanut yield compared to nontreated in conventional- and strip-tillage peanut. Averaged over all herbicide treatments, years, and tillage methods, peanut seeded in twin rows yielded 300 kg/ha more than in single rows. Nomenclature: 2,4-DB; bentazon; diclosulam; chlorimuron; flumioxazin; imazapic; imazethapyr; paraquat; pyridate; common cocklebur, Xanthium strumarium L. #3 XANST; Florida beggarweed, Desmodium tortuosum (Sw.) DC. # DEDTO; ivyleaf morningglory, Ipomoea hederacea (L.) Jacq.; sicklepod, Senna obtusifolia L. # CASOB; peanut, Arachis hypogaea L. ‘Georgia Green’ and ‘C-99R’. Additional index words: Narrow-row; double-row; tillage. Abbreviations: EPOST, early-postemergence; fb, followed by; LPOST, late-postemergence; MPOST, mid-postemergence; POST, postemergence; PRE, preemergence; TSWV, tomato spotted wilt tospovirus; WAP, weeks after planting; WAT, weeks after treatment.